Selective flota l iqsr osi minerals



Patented Sept. l, 1928.

UNITED srAres BAYARD S. MORROW AND KLETEETKO, O]? ANACOIIDA, MdNTANASELECTIVE FLOTJ BELEZON E MINERALS.

Io Drawing.

This invention relates to the selective flotation of minerals,especially the suliid ores and is based upon the useoit cresylic acid asa solvent for and as a: supplemental flotative agent withthio-carbanilid. The use of thio-carbanilid in the concentration ofsulfid ores by the iiotation process is well known. It has been usedwith marked success on copper ores as wellas complex lead-zinc-iron 1ores, both as a dry agent, that is, according to the common practice byfeeding the dry thio-carbanilid to the ore grinding mill and also asaWet agent, that is, in combination with an organic solvent such as thecommon flotation oils andoil mixtures Due to its low solubility inwater, it ismueh more eli'ective as a wet agent than as .a dry agent. Inthe use of thio-carbanilid as a wet agent, the solvent used may beeither one which will directly assist the flotation operation or it maybe one which itself has no flotation properties. Thus the solvent mayhave selective flotation qualities or it may be a frothing agent orboth. The most commonly .used solvent for thio-carbanilid isortho-toluidine, the usual mixture or solution used containing about 80percent of the ortho-toluidine and 20 percent of thio-earbanilid.However even 'with this comparatively dilute solution it is necessary toheat and maintain its temperature at about 45 C. in order to hold thethio-carbanilid in solution. This temperature requirement is highlyobjectionable due to the volatility of the ortho-toluidine which islostby volatilization and the vapors of which moreover are highlyinflammable. The ortho-toluidine itself is etl'ective only as Y .afrothing agent, and when used in excess gives a spongy 'l'roth which isnot desirable for the best flotation results since it tends tocontaminate the concentrate with insolublc material. Another objectionto the use of ortho-toluidine is its cost, the available supply beingfairly limited.

WVe have now found that cresylic acid is an excellent solvent for andsupplemental flotation agent with thio-carbanilid. Cresylic acid is awell-known flotation agent having desirable selective flotationproperties as well as some frothing Value, and is moreover a relativelyinexpensive agent in that it is effective when used in very smallamounts in a flotation circuit.

We have found that thio-carbanilid is soluble in cresylic acid and thatthe result- Application filed Gctober 21, 1925. Serial No. 63,992.

ing solution is very effective as a fiotation' agent. Owing to itshighly selective qualifamount of ortho-toluidine. to the, mixture.

Thus, a mixture or solution of 20 parts by weight of ortho-toluidine andparts by weight of cresylic acid and 20 parts by weight ofthio-carbanilid will hold the thiocarbanilid in solution indefinitely at30 0., and for 24 hours at 20 C. In general, both 'cresylic acid aloneand a mixture of oresylic acid and ortho-toluidine have the advantageover ortho-toluidine aloneas solvents for thio-carbanilid in that theywill hold more ot the thio-carbanilid in solution at a giventemperature. This greater solubility of the thio-carbanilid in cresylicacid or in a mixture of cresylic acid and ortho-toluidine makes possiblethe employment of lower temperatures which in turn reduces the firehazard and the danger to the health of work men due to poisonous fumes,and further more avoids the loss of solvent by volitization and thusinsures the retention of the thio-carbanilid in solution. The lower costof the cresylic acid as compared with orthotoluidine also is a directeconomic advantage.

As previously stated, thio-carbanilid is more effective when used as awet agent, that is, in solution than when used as a dry agent, that is,added to the ore pulp in its dry state in the ball mill. Due to theincreased amount of thio-carbanilid which may be retained in solution incresylic acid or in a mixture of cresylic acid and ortho-toluidine anddue to the less violent :trothing characteristics of cresylic acid or amixture of cresylic acid and ortho-toluidine as compared toortho-toluidine alone, it is possible to use all of the thio-carbanilidrequired for the flotation in the form of a solution, thus entirelydispensing with the customary supplemental addition of drythio-carbanilid to the ore pulp in the ball mill. This results in adirect saving of thiocarbanilid.

The principal advantage in the use of The improved metallurgical resultsare illustrated by the following tables:

1. Using a solution of parts of thiocarhanilid in a mixture of 60 partsof cresylic acid and 20 parts of ortho-toluidine.

Assays Weight Per For For Per Per cent cent gi r 3d cent cent zinc leadp 5 e g iron 11130] per 0T0 A a. 100 10. 8 i 2. (i 0. 29 5. 5 009 3. lZinc COIICL. 18. 9 53. 3 5. 8 0. 75 18. 8 030 3. 9 5. 2 Lead CODCIJ. l.6 (i. 5 (i8: 0 3. 10 66. l 050 2. 1 0. 5 'l illllngflin 79. 3 0. 7 0. O.07 1.0 003 2. 5

II. Using thio-carbanilid in its natural state added to the ball millwith thio-earhanilid in solution in ortho-tolulcline.

reeasee The metallurgical advantages indicated by the foregoing tablesare as follows:

(a) A decrease in the loss of zinc and lead in the tailings or in thediscard.

(6) Increased recovery of zinc and lead in the concentrates.

(0) Increased concentration of zinc and lead in the concentrates. I

((Z) Increased recovery of zinc in the subsequent treatment oftheconcentrate due to the lower iron content thereof.

The scope of the invention is indicated in the appended claims.

We claim:

1. As a flotation agent a solution comprisinq' cresylic acid andthio-carbanilid.

As a flotation agent a solution comprising cresylie acid,thio-carhanilid and 0rthotoluidine.

3. As a flotation agent a mixture of about 20 parts by weight of:ortho-toluidine, 20 parts by weight of thio-carbanilid and 60 parts byweight of cresylic acid.

In testimony whereof, we afiix our signatures.

BAYARD S. MORROW ERNEST KLEPETKQ.

